what's the best price

NoHyperbole

If the dealership sold this 2015 370Z as a used car, it would have to have been previously titled and registered, and I'm sure the salesperson would know that ahead of time because there would be license plates on the car or a registration sticker in the window.

Now, if this car was extensively damaged in transport or at the dealership and was subsequently repaired/rebuilt, then I could see that large of a discount.

However, the OP mentioned that the dealership lowered the price after he vehemently complained about the incorrect information he was given regarding the car's odometer reading (15 miles vs. ~500), which is why I am skeptical, because this would represent a discount of about $20 per mile off MSRP. While a new car with 500 miles should be discounted somewhat, I don't think the excess mileage could affect the price to this magnitude.

nis350

I agree with everything you said. It could also be a 'returned' vehicle from a customer for whatever reasons with 500 miles. Why would a 2015 new car with 500 miles that was sold in 2014?

There is no way a dealer would discount $10k off a 2015 new car in 2014 just because the car has 500 'clean' miles. You wouldn't even get that kind of discount during the great recession in 2008 or that dealer would probably be out of business if they did.

I am sure the dealer has to disclose any adverse information relating to the car, but it might not be shared by the current owner here.

NoHyperbole

You are exactly right. The current owner has most likely omitted some relevant details, assuming everything else is true.